The factors which regulate the development of adipose tissue mass and the mechanisms which lead to obesity are poorly understood. The objectives of this research proposal include (a) determining the activity patterns of several enzymes associated with proliferation and differentiation in adipose tissue: DNA polymerase, thymidine kinase, esterase, lipoprotein lipase and hormone-sensitive lipase, (b) assessing changes in these enzymes as a function of normal or abnormal growth, and (c) utilizing the results to develop a technique for use in predicting the onset of hyperplastic obesity in young infants and children.